The present invention relates to liquid-level valving devices. It is especially useful with respect to automatic relief valves, particularly air-relief valves used to release air (or other gases) from lines carrying water (or other liquids), and is therefore described below with respect to that application.
Air in water lines can be extremely dangerous, since it can produce water hammer of such pressure as to burst a pipe. Various types of air-relief valves have been provided to release such air from the pipe without permitting the water (or other liquids) to escape.
One type of air-relief valve, called the small-orifice type, automatically releases air that may accumulate under pressure in sections of a pipe line during normal working conditions when the line is under pressure. This type usually includes a buoyant ball for sealing the orifice. As air accumulates in the upper part of the valve chamber, it gradually depresses the water level, reducing the upward thrust on the ball until the ball drops and the high pressure air discharges. Upon the discharge of the air, the pressure drops, and the water level rises again until the ball reseals the orifice. The buoyant balls in such valves are usually of very large diameter and of heavy weight to ensure they will not be held against the orifice by air alone, and therefore such valves are very bulky and costly.
The present invention provides a liquid-level valving device which is particularly useful for producing a new type of automatic relief valve for separating a gas from a liquid, and vice versa. The present invention also provides a novel automatic relief valve including the above valving device.